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l g y Il @MRM/Lapo@ C. H. HOPKINS & G .l W. KNIGHT'. JACK SCREW.

Patented Oct. 41887.

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,Wm Vgn@ Swoon/Sow' Uarwf. Jia/waas Geary? UNITED STATES PATENT OFFICE.

CHARLES H. HOPKINS AND GEORGE W. KNIGHT, OF LYNDONVILLE, VERMONT.

JACK-SCREW.

SPECIFICATION forming part of Letters Patent No. 371,068, dated October 4, 1867.

Application tiled June 9, 1h87. Serial No. 240,790. (No model.)

T @ZZ whom may concern:

Immediately outside of the small beveled Beit known that we, CHARLES H. HOPKINS l gear E a ratchet-wheel, F, is mounted and and GEORGE W. KNIGHT, citizens ot' the United States, residing at Lyndonville, inthe county of Caledonia and State of Vermont, have invented a new and useful Improvement in JackScrews, ot which the following is a specification.

Our invention relates to an improvementin lc jack-screws; and it consists in the construction jack-screw which is simple and eft'ective'in its construction and operation, strong and durable, easily handled and readily understood,

positive in its result, and cheaply manufactured. We attain this object by the construction of jack-screw illustrated in the accompanying drawings, wherein like letters oi' referenceindicate similar parts in the several views, and in which-u Fignre l is a perspective view of our improved jack-screw. Fig; 2 is a vertical sectional view of the same. Fig. 3 is an elevation of the inner side of the operating-handle, showing the spring actuated double acting pawl and ratchet shown inconnection therewith.

A indicates a suitable standard, which is constructed hollow and has a base-rest, a2. As shown in Fig. l, a nut, B, in the form of a bevel-gear, is mounted on the top portion of this standard A, and has a screw, C, passing therethrough,which projects downwardly into the internal portion of the said standard A. The head. c of the screw G projects slightly above the upper surface of the nut or beveled gear B, for the purpose of bringing the weight of the object to be raised directly upon the head c of the said screw, and not interfere with the perfect operation and revolution ofthe beveled gear or nut B.

Mounted in a boss formed at one side of the standard A is a stub-shaft, D, upon the inner portion of which, adjacent to the said boss, a

small bevel-gear, E, is mounted, and engages with the bevel gear or nut B on the top ofthe standard A.

formed integrally with the said wheel E, and

is adapted to be engaged by a double integral' pawl, F', pivotally mounted in connection with the handle G, mounted on the said shaft Don the outer side of the ratchet-wheel F.` A clamping-nut, H, is inserted on the end of the shaft D, to retain the parts in their relative operative position.

The handle G has a torsion-spring, S, connected thereto, the upper end of which engages with theslot f, formed in the lower end ofthe double pawl F. The lower end of this spring is provided with a stud orpin, f2, which is adapted to be inserted in either one of two apertures, f j", formed near the two outer edges of the handle G. rl`he length of said spring from its upperend to the stud f is slightly greater than the distance from the inner end ofthe socketf to either oftheholesf, whereby when said stud is inserted in either of said sockets the spring will be forced out of direct alignment with the pawl F, and will incline it in an opposite direction; hence, when the said stud or pin f2, as fully shown in Figs. 2 and 3, is inserted in the aperture f on the left ofthe handle G, the iingerf of the double pawl is adapted to engage with the ratchet F. When the said stud or pin is inserted inthe opposite aperture, the linger f 4 of the said double pawlis thrown in connection with the ratchet F, and the iinger f3 thrown out of connection therewith. Thus it will be seen that the said pawl F can be arranged to work in either direction, as may be desired.

The handle G is adapted to be operated by hand by means of the wrist-pin g, formed therewith. A suitable driving mechanism can be connected thereto, as will be obvious.

The operation of our improved jack-screw will be as follows: The handle G being operated, the double pawl F', thrown into Inotion thereby, engages with the ratchet-wheel F, which revolves the beveled gear E, said and the wheel B turning causes the said screw to rise, as will be readily understood. By this means the main operating mechanism ot' the jackscrew is allowed to remain stationary as regards elevation, while the screw itself is grad ually raised without turning. By meansof our form of construction of lifting jack-screws a great power is brought to bear upon the screw with but a small force, and byineans of the double action rof the pawl heretofore described the motion of this screw may be readily reversed when necessary.

The novelty and utility of our improved device being apparent, it need not further be enlarged upon herein.

It is obvious that many minor changes in the construction and arrangement of the various parts-may be made and substituted for those herein shown and described without departing in the least from the nature and principle of our invention.

We are aware that previous to our invention it has been proposed to construct a screwjack wherein a dog was employed for engaging the pinion to effect its rotation in either direction. NVe are also aware that it is not new to employ a latch' which can be so turned as to hold the operatinglever out of engagement with the ratchet-wheel. We are also aware that it is not newto employ adouble acting pawl controlled by an independent bent spring. Our invention will be readily distinguished from the foregoing in .that the pawl-controlling springis connected to said pawl, and is adapted to be secured tothe ratchet-lever in a series of different positions. An important feature consists in the fact that the sp1-ing is slightly longer than the point where it is to be attached on the lever, so that said spring will exert a tension to properly maintain the connection and prevent accidental disengagement.

Having thus described our invention, We elaimn 1. The combination of the standard A, internally screw-threaded, the bevel -gear B,

mounted on the upper end of the standard, the screw G, passing thereth rough and into the internal part of the standard, the shaft D, formed integral with a portion of the standard and projecting horizontally therefrom, the bevel-gear mounted on the said shaftand meshing with the gear B, the ratchet wheel F, formed integral with the gear E, the lever G, having the apertures f f near its opposite edges at its outer end, the double-acting pawl having the teeth f3 f4, adapted to engage the ratchet-wheel F and provided with the slot f in its lower end, the said pawl being pivoted on thc lever G, and the torsional spring S, having one end secured in the said slotf, and its other end extending slightly beyond said apertures and provided with the pin f2, adapted to engage the said apertures j in the lever, substantially as specified.

2. In a jack-screw, the combination,with the standard A, a screw, C, therein, a bevelgear, B, seated in the upper end of said standard and provided with an internal screw-thread engaging the thread on said screw-shaft D, a bevel-gear, E, mounted on said shaft D of said standard, at right angles to said gear B and engaging therewith, a ratchetwheel, F, integral with said gear E, and a handle, G, loosely mounted on said stub-shaft, of a double pawl, F', pivoted on said handle and provided with a slot, f, in its outer end, and atorsion-spring,

S, one end of which enters said slotf, and the.

other end ot which is provided with a later ally-projecting pin,f2, adapted to enterholesf in said handle, said pin being normally farther from the pivot of said pawl than said holes, as and for the purpose set forth.

In testimony that we claim the foregoing as our own we have hereto affixed oursignatures in presence of two Witnesses.

CHARLES H. HOPKINS. GEORGE YV. KNIGHT.

Vitnesses:

HoMER C. NVILsoN, GEO. C. CnHooN. 

